Last week the observing schedule was halted due to high radiation associated with solar flare activity. The loads were halted on Apr 28 at 12:52am EDT through a ground command to execute the SI Safing SCS 107. The projected orbital radiation dose was significantly higher than the threshold allowed for ACIS. The loads were rebuilt and resumed on Apr 29 at 12:40am EDT once the radiation levels had subsided to an acceptable level. Observations of Arp 270 and 3C 228 were impacted and will be rescheduled in a future load.

A key real-time activity was completed on May 2 with the successful uplink and on-orbit test of the Objective Transmission Grating (OTG) flight software patch. The patch allows once more for autonomous operation of the Low Energy Transmission Grating from the daily load. LETG moves have been made with real-time hardware commanding since Aug 2000 to work around anomalous HETG retract limit switch indications that inhibit software commanded LETG motion. In the case of HETG retractions, the new software patch uses data from the potentiometer and grating motion timing to determine the retracted state. Operation of the LETG from the daily loads will commence following approval of the associated ground operations products.

The planned observations for the coming week are shown below and is dominated by HETG observations.